Field of the Invention
The present invention relates to improvements in apparatus for taking core tissue samples of, for example, the male prostate or other internal organs at locations corresponding to surface irregularities that can be palpated by the fingertip of a physician (or technician). More specifically, it relates to apparatus for decreasing the risk of finger puncture and improving the accuracy of the biopsy of lesions of interest.
Discussion of the Prior Art
During routine digital examination of the prostate, it is common for the examiner to use his or her fingertip to probe the initial 10 centimeters or so of the rectum to detect any suspicious surface irregularities (e.g., lesions or nodules) that can be felt on the inner surface of the rectal wall or the outer surface of the prostate gland. Having manually palpated irregularities on or through the wall of the rectum, it is often desirable to take a core biopsy of one or more areas of these lesions for subsequent analysis.
In biopsying the irregularities noted above, it is essential that the examining person accurately position the biopsy needle onto a irregularity of interest. It is also essential to accurately position the palpating fingertip out of “harm's way” at the time the biopsy is performed. A “needle stick’ is not only painful to the recipient, but it also can result in the transmission of serious diseases to the examiner biopsying the lesion. To achieve this accuracy during the biopsy procedure, the examiner must simultaneously maintain the position between his or her palpating fingertip and the irregularity of interest, while maneuvering the free end of a biopsy needle assembly to a position closely spaced from the palpating fingertip. Having done so, the physician then activates a triggering mechanism that causes the biopsy needle to quickly reciprocate in axial directions, first moving in a direction to penetrate the irregularity to excise a core sample therefrom, and then moving in an opposite direction in which the needle is withdrawn from the sample and returned to its sheath.
In taking tissue samples as described above, it will be appreciated that the physician must be exceedingly careful to avoid being accidentally injured by the tip of the biopsy needle. Since, at the time of taking the sample, neither the mass of interest nor the tip of the biopsy needle can be visualized, the physician must rely on his or her sense of touch to assure the accuracy of the procedure and his or her safety in performing the procedure. The prospect of an accidental needle stick is exacerbated by the need to position both the needle tip and the palpating fingertip as close as possible to the lesion of interest at the time the biopsy is taken. Generally, the closer this spacing, the higher the accuracy of the biopsy and, unfortunately, the greater the risk of an accidental finger stick by the needle.
The above-noted close spacing among a palpating fingertip, the tip of a biopsy needle and an irregularity of interest will be appreciated from the prior art drawings of FIGS. 1-4 hereof. These drawings have been taken from U.S. Pat. No. 4,600,014 to Beraha. This patent publication discloses a relatively early mechanical device for taking core samples of a prostate gland 40. As shown, the device includes a handle 44 portion designed to be held in the palm of a physician's gloved right hand 74 during the biopsy procedure. Forwardly extending from, and rigidly mounted to the handle, is an elongated, relatively rigid guide tube 30 having a slidably-mounted cannula 20 therein. The latter typically comprises a hollow stainless steel tube 21 having a sharpened distal end 22. As shown in FIGS. 2-4, cannula 20 slidably supports an internal tissue-sampling stylet 10 having a sharpened distal end 12. Together with cannula 20, stylet 10 defines a biopsy assembly BA.
As noted above, cannula 20 is axially movable within the guide tube 30, and its axial position is controlled by the position of a manually movable tab 46 that is slidably-mounted on the handle 44 and rigidly connected to the cannula. Axial movement of the stylet 10 within the cannula 20 is controlled by a knob 50 that is also slidably mounted on the handle 40. As best shown in FIG. 3, a transverse sampling slot 14 is formed in the stylet wall near the sharpened distal end of the stylet. In use, when knob 50 is moved forwardly, the sharpened end 12 of the stylet will project forwardly of the cannula end 22 to a position in which it may be is inserted into the prostate. When so positioned, a portion of the prostate tissue displaced by the stylet will fill the slot 14. At this time, forward movement of tab 46 will cause the sharpened distal end cannula 20 to slice through the prostate and isolate that portion of the prostate located within slot 14 of the stylet. The isolated portion of the prostate within slot 14 constitutes the core sample of interest. Having taken the core sample, the cannula and its internal stylet are then withdrawn from the prostate and returned to the guide tube 30.
According to the disclosure of the above-noted patent, the apparatus disclosed is used as follows: Referring to FIG. 1, the physician first places the handle 40 in the palm of the right hand with the thumb tab 46 facing outward. Prior to this, the needle assembly is loaded into the guide tube so that, while the sharpened distal end of the cannula does not extend beyond the distal end of the guide tube, the sharpened distal end of the stylet extends slightly beyond the guide tube end. This configuration is shown in FIG. 2. The tip of the index finger 76 is then placed at the distal end of the guide tube 30, and the stylet 10 is moved to a position in which its sharpened tip 12 is “forced” against the physician's fingertip. Using the right hand only, the physician inserts the index finger and guide tube 30 into the patient's rectum and contacts the prostate gland. The physician then palpates the gland to locate a suspicious surface irregularity. (In doing this, it is assumed that the physician releases contact between the fingertip and the sharpened stylet tip. Having located an irregularity of interest, the physician will then force the protruding distal end of the stylet into the irregularity, as shown in FIG. 2 and then advance tab 46 forwardly to cause a desired penetration of the of the stylet into the prostate, e.g., to an extent shown in FIG. 3. Then, the physician uses the left hand 78 to push knob 50 forwardly, thereby causing the sharpened end cannula 20 slice through the prostate to capture the core sample in the transverse slot 14 of the stylet. See FIG. 4.
From the foregoing, it will be appreciated that there may be significant safety issues in using the apparatus described. For example, the suggested initial creation of a contact “force” between the physician's fingertip and the stylet tip may well cause a needle stick even before the apparatus is inserted into the rectum. Further, upon removing the fingertip from the sharpened end of the stylet in order to explore (i.e., palpate) the surface of the prostate, an uncertainty is created between the respective positions of the fingertip and the sharpened stylet tip. In such case, movement of the stylet tip to penetrate a nodule of interest without knowing exactly where the fingertip is located may also cause a needle stick of the physician's fingertip. Also, because of this uncertainty, the accuracy of the biopsy may be compromised, causing an unintended portion of the prostate to be biopsied.